Phase 1 Trial of SYNC-T Immunotherapy Reports Longer-Term Survival Data in Prostate Cancer

Updated results provide longer-term survival data for SYNC-T Therapy SV-102, an experimental personalized immunotherapy evaluated in patients with metastatic prostate cancer.

SYNC-T uses a two-step approach. First, a selected tumor lesion undergoes partial cryolysis, releasing patient-specific tumor antigens. An immunotherapy mixture called SV-102 is then injected directly into the treated area. It contains four components: anti-PD-1 and anti-CTLA-4 antibodies, a CD40 agonist antibody, and CpG-ODN, a TLR9 agonist. The objective is to stimulate immune cells against the patient’s own cancer antigens and generate a systemic antitumor response, potentially affecting metastases beyond the treated lesion.

The original phase 1 trial was an open-label, single-arm study conducted in Mexico. It enrolled 15 patients, including ten with metastatic castration-resistant prostate cancer (mCRPC) previously treated with hormonal therapies and five with metastatic hormone-sensitive disease (mHSPC) who had refused androgen deprivation therapy. Patients received image-guided partial tumor cryolysis followed by intratumoral SV-102 administration every four weeks, for up to 12 cycles.

Previously reported results showed an 87% objective response rate and a 40% complete radiological response rate following independent review.

The new analysis, with a median follow-up of 29.6 months, reported 80% overall survival at 24 months, with 12 of the 15 patients alive. Median overall survival had not been reached in the combined population.

Among patients with mCRPC, median overall survival was 27.9 months, with a two-year survival rate of 70%. All five patients with mHSPC were alive at 24 months. Of the six patients who achieved complete radiological responses, three remained disease-free after 26.5–35.3 months.

The treatment was generally well tolerated, with 95% of treatment-emergent adverse events classified as grade 1–2. No grade 3–4 immune-related toxicities were reported.

These findings have supported the development of LEGION-100, a multicenter phase 2a trial specifically investigating SYNC-T SV-102 in mCRPC. Unlike the original study, LEGION-100 focuses on patients with castration-resistant disease and is designed to provide a more extensive assessment of treatment activity, including radiological responses using RECIST 1.1 and PCWG3 criteria. 

Despite the encouraging early findings, important limitations remain. The original trial included only 15 patients, combined hormone-sensitive and castration-resistant disease, and lacked a control group. Consequently, the reported survival and response rates cannot establish superiority over standard treatments.

Source.

Clinical trial.